Enhanced immunogenicity using leukotoxin chimeras

Abstract

New immunological carrier systems, DNA encoding the same, and the use of these systems, are disclosed. The carrier systems include chimeric proteins which comprise a leukotoxin polypeptide fused to a selected antigen. The leukotoxin functions to increase the immunogenicity of the antigen fused thereto.

We claim: 
     
       1. A DNA construct encoding a chimeric protein, said DNA construct comprising a first nucleotide sequence encoding a leukotoxin polypeptide capable of activating helper T-cells directed to a selected antigen, operably linked to a second nucleotide sequence encoding said selected antigen. 
     
     
       2. The DNA construct of claim 1 wherein said second nucleotide sequence encodes somatostatin (SRIF), or an epitope thereof. 
     
     
       3. The DNA construct of claim 2 comprising the nucleotide sequence depicted in SEQ ID NO:9. 
     
     
       4. The DNA construct of claim 1 wherein said second nucleotide sequence encodes gonadotropin releasing hormone (GnRH) comprising the amino acid sequence Gln-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly, or an epitope thereof. 
     
     
       5. The DNA construct of claim 4 comprising the nucleotide sequence depicted in SEQ ID NO:11. 
     
     
       6. The DNA construct of claim 1 wherein said second nucleotide sequence encodes bovine rotavirus VP4, or an epitope thereof. 
     
     
       7. The DNA construct of claim 6 comprising the nucleotide sequence depicted in SEQ ID NO:13. 
     
     
       8. An expression cassette comprised of: (a) the DNA construct of claim 1; and   (b) control sequences that direct the transcription of said construct whereby said construct can be transcribed and translated in a host cell.   
     
     
       9. An expression cassette comprised of: (a) the DNA construct of claim 2; and   (b) control sequences that direct the transcription said construct whereby said construct can be transcribed and translated in a host cell.   
     
     
       10. An expression cassette comprised of: (a) the DNA construct of claim 4; and   (b) control sequences that direct the transcription said construct whereby said construct can be transcribed and translated in a host cell.   
     
     
       11. An expression cassette comprised of: (a) the DNA construct of claim 6; and   (b) control sequences that direct the transcription said construct whereby said construct can be transcribed and translated in a host cell.   
     
     
       12. A host cell stably transformed with the expression cassette of claim 8. 
     
     
       13. A host cell stably transformed with the expression cassette of claim 9. 
     
     
       14. A host cell stably transformed with the plasmid of claim 10. 
     
     
       15. A host cell stably transformed with the plasmid of claim 11. 
     
     
       16. A method of producing a recombinant polypeptide comprising: (a) providing a population of host cells according to claim 12; and   (b) growing said population of cells under conditions whereby the polypeptide encoded by said expression cassette is expressed.   
     
     
       17. A method of producing a recombinant polypeptide comprising: (a) providing a population of host cells according to claim 13; and   (b) growing said population of cells under conditions whereby the polypeptide encoded by said expression cassette is expressed.   
     
     
       18. A method of producing a recombinant polypeptide comprising: (a) providing a population of host cells according to claim 14; and   (b) growing said population of cells under conditions whereby the polypeptide encoded by said expression cassette is expressed.   
     
     
       19. A method of producing a recombinant polypeptide comprising: (a) providing a population of host cells according to claim 15; and   (b) growing said population of cells under conditions whereby the polypeptide encoded by said expression cassette is expressed.